Critical Enhancement of Photorefractive Beam Coupling

Abstract

We show that a hybridization of the optical and material nonlinearities takes place near the threshold of the subharmonic generation in photorefractive crystals. It results in a critical (with a singularity) enhancement of the rate of spatial amplification of light waves and leads to a variety of new optical critical phenomena.

Solitonlike Beam Propagation along Light-Induced Singularity of Space Charge in Fast Photorefractive Media

“…As shown recently, hybridization of these nonlinearities is able to provide an almost infinite growth (singularity) of the rate of spatial amplification when approaching the threshold of the subharmonic generation [7].…”

“…Among them are propagation of solitons [1] and surface waves [2], pattern formation [3], parametric scattering [4], subharmonic generation [5,6], and critical enhancement [7]. Most of the mentioned PR effects are generic; they are easily accessible at low light intensities and distinguished by a wide variety of forms.…”

Exact bright and dark spatial soliton solutions in saturable nonlinear media

“…Equation (1) has shown a number of applications in plasma physics [16] and nonlinear optics [17,18,19], specifically in photorefractive media. Photorefractive materials manifest a wealth of nonlinear phenomena which include the propagation of solitons [20,21,22,23,24], surface waves [26] and slow light [25], pattern formation [27], charge singularities [28], and critical enhancement [29]. The case with α = 1 (which corresponds to non-centrosymmetric photorefractive media) has been throughly studied, and solitary wave solutions in the form of bright, black and grey solitons have been found numerically [20,21,22,30].…”

Space-Charge Wave Effects in Photorefractive Materials

“…Formation of light-induced discontinuities of the refractive index and their impact on the nonlinear beam propagation in AC-biased sillenite crystals were predicted in 1999-2001 [72][73][74][75]. The effect of critical enhancement of PR beam coupling near the threshold of subharmonic generation was presented in 2000-02 [76][77][78]. The effects of temporal and spatial rectification of SCWs in the sillenites have been investigated recently in [79,80].…”

“…By setting a 0 , a à 0 / exp (Gx) in (5.45), (5.46), we obtain for two possible values of the gain factor (spatial increment) G [76]:…”